/* 侧边栏链接 */
#sidebar a {
    display: block;
    color: black;
    padding: 0.5em 1em;
    text-decoration: none;
    min-width: 8em;
}
  
/* 活动/当前链接 */
#sidebar a.active {
    background-color: #4CAF50;
    color: white;
}
  
  /* 鼠标悬停链接 */
#sidebar a:hover:not(.active) {
    background-color: #555;
    color: white;
}